A conventional city water distribution system is a network of pumps, pipelines, storage tanks, fire hydrants, and the like. The water main pipes are typically buried underground, in dedicated easements. A water distribution system delivers quantities of water at pressures sufficient for supply customers and firefighting equipment while avoiding excess pressure which could cause leaks and pipeline breaks. Water customer services are attached to the water main, and water is carried from the water distribution system into customers' homes or businesses.
Fire hydrants are typically fed by an underground supply pipe and typically include underground shut-off valves which control the flow of water to each hydrant. Fire hydrants contain manually operable valves which are operated by a fireman to release water from the underground supply pipe in an event of a fire or during a training exercise. Also, hydrants may be opened by city workers or others in order to clear sedimentation from the water mains. Typically, the hydrant valve is located underground. Except in tropical climates where the ground does not freeze, it is generally necessary to bury below the frost line all of the parts of the system which normally retain standing water or slowly moving freezable liquids. A drain valve is normally open, draining the hydrant barrel while the hydrant valve is closed.
The hydrant valve is usually controlled by a stem extending vertically from the buried valve and passing through the top of the hydrant. A shut-off auxiliary valve, which is separate from the hydrant valve, is usually provided with an access conduit extending vertically to a removable access cover located at ground level adjacent to the hydrant. The access cover is removed and a removable wrench, commonly known as a valve key, is inserted through the access conduit to operate the shut-off valve.
A water surge can be a severe problem in a distribution system. A water surge results when a valve at one point in a distribution system is opened or shut suddenly, creating shockwaves of moving water upstream and downstream of that valve. In addition, when a pump or other source providing pressure on the water in the main is actuated, additional flows are created or diminished. Since water is essentially incompressible, it does not absorb the energy of the shockwave, but transmits it throughout the distribution system to nearby or distant parts of the system which are not isolated behind a closed valve. The turbulence created by the shockwave seeks a release point. Elevated water tanks are common release points but often are not close to the source of turbulence. Without a planned release point, the turbulence may create its own release point at a weak point in the distribution system, causing a water main break or other damage to the distribution system.
A water surge is capable of parting joints, breaking water mains and other components of the system. Since the system is mostly buried, occasionally time is required to pinpoint the damage area and then correct the resulting damage. The water escaping from the damaged system can cause a pressure failure, a pavement collapse, or other damage. It is sometimes very dangerous to repair. The danger occurs with trench cave-ins during working and with the possibility of breaking, or causing an explosion of a gas or other utility line.
Water main breaks are a costly and time consuming problem for municipalities. A system and method for water surge protection may minimize the frequency of water main breaks. Thus, there is a need for a system and method for protecting a water distribution system from main breaks caused by sudden pressure spikes in the distribution system.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.